Manufacturing method capable of improving surface quality of low carbon and boron steel wire rod

Abstract

The invention discloses a manufacturing method capable of improving the surface quality of a low carbon and boron steel wire rod. The manufacturing method comprises continuous casting and hot rolling. In the continuous casting process, conditions are controlled as follows: the superheat degree is controlled at 25 to 40 DEG C, the continuous casting speed is 2.6 to 2.85 m / min, the crystallizer cooling water amount is 1,680 to 1,720 L / min, the vibration frequency of a crystallizer is 160 to 200 Hz, and the amplitude is 6.5 to 8.0 mm. According to the manufacturing method, by optimal adjustment of continuous casting crystallizer process parameters and secondary cooling process parameters, initial stepped cooling of the surface of a continuous casting billet is realized, and the heat stress in a continuous casting process is reduced; meanwhile, a high-temperature fragile region caused by adding of a boron element in low carbon and boron steel is avoided; formation of a crack defect on the surface of a low carbon and boron steel continuous casting billet can be effectively prevented, and control over the surface quality of the low carbon and boron steel wire rod finished product is facilitated; and due to the influence of BN (boron nitride) on high-temperature plasticity in heating and rolling processes of the low carbon and boron steel billet, the influence of improper control over the rolling temperature of the low carbon and boron steel on the surface quality of the wire rod finished product is reduced or eliminated.

Description

technical field [0001] The application relates to the technical field of iron and steel metallurgy, in particular to a manufacturing method for improving the surface quality of low-carbon boron-added steel wire rods. Background technique [0002] Boron-containing steel refers to steel with boron as the main alloying element. A very small amount (5-30ppm) of boron can significantly improve the hardenability of steel, and can improve the overall performance of steel while reducing production costs. However, the addition of B also greatly increases the crack sensitivity of the steel. Therefore, by adding Al or Ti to the steel, the influence of B on the surface quality of the low-carbon boron-containing steel can be reduced. Both methods are based on different thermodynamic conditions, by adding elements that are easier to combine with [N] elements to reduce or avoid the formation of BN, thereby reducing the accumulation of BN at grain boundaries. However, the AlN formed after ...

AI Technical Summary

Problems solved by technology

However, the AlN formed after the addition of Al is also easy to gather and precipitate along the grain boundary, which will also have a greater impact on the high-temperature shaping of the steel, but its precipitation temperature range is different from that of BN, so the surface temperature control range in the continuous casting process is different. ; and after adding Ti element, TiN will precipitate at the grain boundary and within the grain during the solidification process, gather less at the grain boundary, and have less influence on high-temperature plasticity, but the chemical activity of Ti element is relatively large, and it is easy to combine with O, N Elements combine to form TiO x TiN and TiN will cause nozzle nodulation, which will affect the pourability of the continuous casting process, and will also cause large fluctuations in the liquid level of the mold, thereby affecting the surface quality of the continuous casting slab

Therefore, the method of adding Al or Ti elements to the steel cannot improve and solve the problem of the surface quality of the low-carbon boron-added steel, and also increases the production cost.